车联网环境下基于模糊逻辑的交通拥堵检测方法

针对现有的道路交通拥堵检测方法的不足,提出了一种基于V2V的道路交通拥堵检测方法。首先基于V2V的方式实时获取邻居车辆状态信息,建立车辆邻居表;其次依据车辆行驶速度、车流密度、交通拥堵评级体系构建模糊控制器,完成本地交通拥堵水平的估计;然后通过车车通信进行邻居车辆交通拥堵状况的查询,并根据大子样假设检验验证本地交通拥堵水平值,完成所在区域交通拥堵水平的检测;最后基于Veins平台搭建仿真测试场景,仿真对比了拥堵检测结果的准确率,同时测试车辆节点的退避时槽数量和接收广播数据包的数量。实验结果表明, 提出的道路交通拥堵检测方法实现的拥堵检测准确率分别比线圈法和CoTEC法提高了5.5%和7.5%;提出的道路交通拥堵检测方法实现的车车通信网络拥塞比CoTEC法降低了90.8%,并且在未发生交通拥堵时通信节点的通信负载显著降低。     

Adaptive green traffic signal controlling using vehicular communication

The importance of using adaptive traffic signal control for figuring out the unpredictable traffic congestion in today’s metropolitan life cannot be overemphasized. The vehicular ad hoc network (VANET), as an integral component of intelligent transportation systems (ITSs), is a new potent technology that has recently gained the attention of academics to replace traditional instruments for providing information for adaptive traffic signal controlling systems (TSCSs). Meanwhile, the suggestions of VANET-based TSCS approaches have some weaknesses: (1) imperfect compatibility of signal timing algorithms with the obtained VANET-based data types, and (2) inefficient process of gathering and transmitting vehicle density information from the perspective of network quality of service (QoS). This paper proposes an approach that reduces the aforementioned problems and improves the performance of TSCS by decreasing the vehicle waiting time, and subsequently their pollutant emissions at intersections. To achieve these goals, a combination of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications is used. The V2V communication scheme incorporates the procedure of density calculation of vehicles in clusters, and V2I communication is employed to transfer the computed density information and prioritized movements information to the road side traffic controller. The main traffic input for applying traffic assessment in this approach is the queue length of vehicle clusters at the intersections. The proposed approach is compared with one of the popular VANET-based related approaches called MC-DRIVE in addition to the traditional simple adaptive TSCS that uses the Webster method. The evaluation results show the superiority of the proposed approach based on both traffic and network QoS criteria.     

On-siteDriverID: A secure authentication scheme based on Spanish eID cards for vehicular ad hoc networks

Security in Vehicle Ad Hoc Networks (VANETs) has been a topic of interest since the origins of vehicular communications. Different approaches have been followed as new security threats have emerged in the last few years. The approach of conditional privacy has been widely used as it guarantees authentication among vehicles but not revealing their real identities. Although the real identity of a vehicle can be traced by the authorities, the process to do that is time consuming and typically involves several entities (for instance road authorities that request the identification, license plate records bodies, a judge to allow revealing the identity associated to a license plate…). Moreover, this process is always subsequent to the detection of a road situation that requires knowing the real vehicle identities. However, in vehicular scenarios, authorities would beneficiate from knowing the real drivers’ identity in advance. We propose in this paper On-SiteDriverID, a secure protocol and its application which allows authorities’ vehicles to obtain drivers’ real identities rapidly and on demand on VANET scenarios. Thus, authorities would be able to gather information about drivers and vehicles, allowing them to act in a safer and better manner in situations such as traffic control duties or emergencies. The obtained simulation results in real VANET scenarios based on real maps guarantee that in the 60%–70% of cases the proposed On-SiteDriverID successfully obtains the identity of the drivers.     

A V2I communication-based pipeline model for adaptive urban traffic light scheduling

Adaptive traffic light scheduling based on realtime traffic information processing has proven effective for urban traffic congestion management. However, fine-grained information regarding individual vehicles is difficult to acquire through traditional data collection techniques and its accuracy cannot be guaranteed because of congestion and harsh environments. In this study, we first build a pipeline model based on vehicle-to-infrastructure communication, which is a salient technique in vehicular adhoc networks. This model enables the acquisition of fine-grained and accurate traffic information in real time via message exchange between vehicles and roadside units. We then propose an intelligent traffic light scheduling method (ITLM) based on a “demand assignment” principle by considering the types and turning intentions of vehicles. In the context of this principle, a signal phase with more vehicles will be assigned a longer green time. Furthermore, a green-way traffic light scheduling method (GTLM) is investigated for special vehicles (e.g., ambulances and fire engines) in emergency scenarios. Signal states will be adjusted or maintained by the traffic light control system to keep special vehicles moving along smoothly. Comparative experiments demonstrate that the ITLM reduces average wait time by 34%–78% and average stop frequency by 12%–34% in the context of traffic management. The GTLM reduces travel time by 22%–44% and 30%–55% under two types of traffic conditions and achieves optimal performance in congested scenarios.     

Edge-centric trust management in vehicular networks

A major objective of vehicular networking is to improve road safety and reduce traffic congestion. The experience of individual vehicles on traffic conditions and travel situations can be shared with other vehicles for improving their route planning and driving decisions. Nevertheless, the frequent occurrence of adversary vehicles in the network may affect the overall network performance and safety. These vehicles may behave intelligently to avoid detection. To effectively control and monitor such security threats, an efficient Trust Management system should be employed to identify the trustworthiness of individual vehicles and detect malicious drivers which is the major focus of this work. We propose a hybrid solution, which integrates Edge Computing and Multi-agent modeling in a Trust Management system for vehicular networks. The proposed solution also aims to overcome the limitations of the two commonly utilized approaches in this context: cloud computing and Peer-to-Peer (P2P) networking. Our framework has a set of features that make it an efficient platform to address the major security challenges in vehicular networks including latency, scalability, uncertainty, data accessibility, and malicious behavior detection. Performance of the approach is evaluated by simulating a realistic environment. Experimental results show that the proposed approach outperforms similar approaches from literature for various performance indicators.     

Contention-based forwarding with multi-hop connectivity awareness in vehicular ad-hoc networks

Recent vehicular routing proposals use real-time road traffic density estimates to dynamically select forwarding paths. Estimating the traffic density in vehicular ad hoc networks requires the transmission of additional dedicated messages increasing the communications load. These proposals are generally based on unicast sender-based forwarding schemes. The greedy nature of sender-based forwarding can result in the selection of forwarders with weak radio links that might compromise the end-to-end performance. To overcome these limitations, this paper presents TOPOCBF, a novel contention-based broadcast forwarding protocol that dynamically selects forwarding paths based on their capability to route packets between anchor points. Such capability is estimated by means of a multi-hop connectivity metric. The obtained results demonstrate that TOPOCBF can provide good packet delivery ratios while reducing the communications load compared to unicast sender-based forwarding schemes using road traffic density estimates.     

CATS: An adaptive traffic signal system based on car-to-car communication

Traffic signal controls play an important role in regulating vehicular flow at road intersections. Traditional systems are not capable of adjusting the timing pattern in accordance with vehicular demand. This results in excessive delays for road users. Hence it is necessary to develop dynamic systems that can adjust the timing patterns according to traffic demand. In this paper, the design and implementation of an adaptive traffic signal control system based on car-to-car communication is presented. Also, a clustering algorithm is defined which will assist in estimating the density of vehicles approaching an intersection. The cycle time, which is calculated using the estimated density of vehicular traffic, helps in reducing both the waiting time for vehicles at intersections and queue length. It is also shown that the proposed solution is collision free at intersections. The proposed system is compared with a classic pre-timed system and an adaptive fuzzy logic system. The simulations also show that the data convergence time and the communication delay between vehicles and traffic signals do not compromise the efficiency of the system.     

一种时间最短的交通网络路径求解方法

随着科技的不断发展和人民生活水平的不断提高,汽车的保有量日益增加,交通堵塞问题愈加严重,造成了时间的浪费。为了防止城市交通拥堵,节约驾驶员出行的时间,将路网信息表示成矩阵的形式,建立了车辆行驶时间目标函数。运用拉格朗日乘子法求解目标函数,从而得到各车辆的行驶路径。最后,利用MATLAB实验仿真,在目标函数最小的情况下,能得到车辆的行驶路径,当有利他因子时,更节省出行时间。     

A general framework for modeling shared autonomous vehicles with dynamic network-loading and dynamic ride-sharing application

Shared autonomous vehicles (SAVs) could provide low-cost service to travelers and possibly replace the need for personal vehicles. Previous studies found that each SAV could service multiple travelers, but many used unrealistic congestion models, networks, and/or travel demands. The purpose of this paper is to provide a method for future research to use realistic flow models to obtain more accurate predictions about SAV benefits. This paper presents an event-based framework for implementing SAV behavior in existing traffic simulation models. We demonstrate this framework in a cell transmission model-based dynamic network loading simulator. We also study a heuristic approach for dynamic ride-sharing. We compared personal vehicles and SAV scenarios on the downtown Austin city network. Without dynamic ride-sharing, the additional empty repositioning trips made by SAVs increased congestion and travel times. However, dynamic ride-sharing resulted in travel times comparable to those of personal vehicles because ride-sharing reduced vehicular demand. Overall, the results show that using realistic traffic flow models greatly affects the predictions of how SAVs will affect traffic congestion and travel patterns. Future work should use a framework such as the one in this paper to integrate SAVs with established traffic flow simulators.     

基于激光传感数据的拥堵路口交通信号灯控制

针对城市车流高峰时段的道路拥堵问题,提出基于激光传感数据的交通信号灯智能控制方法研究。在道路两侧均匀布置激光传感器节点,采集实时的激光传感数据和车流量信息,并构建一种两层级的交通信号灯控制模型,以提取的交通路口实时传感数据作为输入项进行模糊推理,并求解出交通信号控制模糊子集,最后推导出当前车流长度、车辆在路口的平均滞留时长及车辆的延误时长等变量,达到缓解交通拥堵,提高通行效率的目的。仿真实验数据表明,提出的拥堵交通信号灯智能控制方法具有良好的控制效果,可以明显减少车辆延误时长,提高道路通行的效率和安全性。     

RFID，GPS和GIS技术集成在交通智能监管系统中的应用研究*

为实现在城市复杂路网情况下对交通车辆的实时监控,并且能通过一定数量的车辆运行状态来判断道路交通的拥挤状况,采用射频识别技术(RFID)对道路上运行的车辆进行动态识别和数据信息交换;依靠全球定位系统(GPS)技术实时获得目标车辆的位置信息,并通过地理信息系统(GIS)将车辆的运行状况以及路网的交通状况以电子地图形式实时地展现给用户。将GPS、GIS与RFID技术综合应用于城市道路交通管理系统中,在此基础上设计出道路交通车辆的全程监控模型和系统框架。对交通监管的信息化建设具有一定的借鉴意义。     

Simulation Exercise on Time Perception Parameters in Discrete-time Dynamic Assignment Models

In order to assess the performance of information systems to road users and of demand management measures, like staggered and/or flexible work times and road pricing, with respect to congestion prevention problems, it is necessary to simulate dynamics of traffic flows on the transport network and users' behaviour. This can be accomplished by taking into account several aspects such as users' information level, travel demand distribution over time and the expected smoothing effect of adopted measures and information systems. Dynamic assignment and arrival time choice models and computational procedures to perform this assessment for various traffic scenarios and hypotheses about users' behaviour are presented in this paper. Moreover, the indicators needed to quantify information systems and demand management effectiveness are identified together with parameters defining traffic scenarios. The main results obtained by applying these models and techniques as deterministic and probabilistic simulation tools are also presented and discussed.     

LPPTE: A lightweight privacy-preserving trust evaluation scheme for facilitating distributed data fusion in cooperative vehicular safety applications

Vehicular networks have tremendous potential to improve road safety, traffic efficiency, and driving comfort, where cooperative vehicular safety applications are a significant branch. In cooperative vehicular safety applications, through the distributed data fusion for large amounts of data from multiple nearby vehicles, each vehicle can intelligently perceive the surrounding conditions beyond the capability of its own onboard sensors. Trust evaluation and privacy preservation are two primary concerns for facilitating the distributed data fusion in cooperative vehicular safety applications. They have conflicting requirements and a good balance between them is urgently needed. Meanwhile, the computation, communication, and storage overheads will all influence the applicability of a candidate scheme. In this paper, we propose a Lightweight Privacy-Preserving Trust Evaluation (LPPTE) scheme which can primely balance the trust evaluation and privacy preservation with low overheads for facilitating the distributed data fusion in cooperative vehicular safety applications. Furthermore, we provide exhaustive theoretical analysis and simulation evaluation for the LPPTE scheme, and the results demonstrate that the LPPTE scheme can obviously improve the accuracy of fusion results and is significantly superior to the state-of-the-art schemes in multiple aspects.     

Deployment of a fully distributed system for improving urban traffic flows: A simulation-based performance analysis

Distributed, cooperative systems dedicated to road traffic self-organization are very attractive, but present some drawbacks. In particular, their cooperative nature makes them fairly inefficient when working with a reduced number of partners. This situation typically corresponds to the deployment stage, during which only a few vehicles cooperate. This time period cannot be avoided when pushing a new system to the market. We are interested in two features that are important for this kind of system: traffic jam detection and traffic alert transmission. For the first feature, we present a theoretical model that anticipates the proportion of equipped vehicles that allows an acceptable level of traffic jam detection, and we validate this model by simulation. For the second feature, we examine two ways to improve the system behaviour when the proportion of equipped vehicles is very low; their efficiency is tested through simulation. This study is innovative because the simulation platform we developed can take into account the directional behaviour of wireless communications in urban context for a low computational cost.     

基于车路云一体化的混合交通系统优化控制综述

汽车行业正在进行智能化与网联化的发展变革,智能网联汽车的出现使交通管理者找到缓解交通拥堵、提高道路安全以及减少能源消耗的一种解决方案.对此,调研混合交通流模型、智能网联汽车协同控制、交通管理等领域的最新成果,系统地论述基于车路云一体化的智慧交通系统优化控制的研究现状与进展.首先,分析基于车路云一体化的混合交通系统的框架,梳理各部分的组成与作用;其次,总结混合交通流的建模方法,探究交通现象本质,归纳各类方法的特点、优势以及局限性;再次,探讨混合交通系统优化控制问题,围绕交通流稳定性、交通安全、交通效率和绿色交通4个方面分析智能化与网联化在交通方面的潜能,并梳理在不同交通场景下的控制对象与控制目标,总结具有借鉴意义的控制方法;最后,对车路云一体化发展进程中存在的问题与挑战进行总结,并对未来发展指明方向.     

智能车技术探讨

近年来,环境污染、交通安全及拥堵等严峻的问题困扰着整个世界。智能汽车的出现是为了建立一种新的交通范例,以便在很大程度上降低驾驶人员的劳动强度,避免汽车碰撞和减轻交通拥堵等。因而,发展新一代的智能汽车就成为了世界主要国家的发展战略目标。提出智能汽车的新定义:以自身装备动力驱动的智能信息系统管控的车辆。它具有5大基本功能特征,即车车交互、车人交互、车路交互、车网交互和绿色节能。车、人、路、网4个交互规定了智能汽车和周边环境之间的协作关系,而绿色节能则关注于清洁节约的能源管理系统。同时,讨论分析了支撑智能汽车发展所需要的新理论和新技术。最后,介绍了在缩微环境下进行的智能车研究和实践,并对未来智能汽车产业的发展方向做出展望。     

A directional data dissemination protocol for vehicular environments

This paper presents a simple and robust dissemination protocol that efficiently deals with data dissemination in both dense and sparse vehicular networks. Our goal is to address highway scenarios where vehicles equipped with sensors detect an event, e.g., a hazard and broadcast an event message to a specific direction of interest. In order to deal with broadcast communication under diverse network densities, we design a dissemination protocol in such a way that: (i) it prevents the so-called broadcast storm problem in dense networks by employing an optimized broadcast suppression technique; and (ii) it efficiently deals with disconnected networks by relying on the store-carry-forward communication model. The novelty of the protocol lies in its simplicity and robustness. Simplicity is achieved by only considering two states (i.e., cluster tail and non-tail) for vehicles. Furthermore, vehicles in both directions help disseminating messages in a seamlessly manner, without resorting to different operation modes for each direction. Robustness is achieved by assigning message delivery responsibility to multiple vehicles in sparse networks. Our simulation results show that our protocol achieves higher delivery ratio and higher robustness when compared with DV-CAST under diverse road scenarios.     

Red Swarm: Reducing travel times in smart cities by using bio-inspired algorithms

This article presents an innovative approach to solve one of the most relevant problems related to smart mobility: the reduction of vehicles’ travel time. Our original approach, called Red Swarm, suggests a potentially customized route to each vehicle by using several spots located at traffic lights in order to avoid traffic jams by using V2I communications. That is quite different from other existing proposals, as it deals with real maps and actual streets, as well as several road traffic distributions. We propose an evolutionary algorithm (later efficiently parallelized) to optimize our case studies which have been imported from OpenStreetMap into SUMO as they belong to a real city. We have also developed a Rerouting Algorithm which accesses the configuration of the Red Swarm and communicates the route chosen to vehicles, using the spots (via WiFi link). Moreover, we have developed three competing algorithms in order to compare their results to those of Red Swarm and have observed that Red Swarm not only achieved the best results, but also outperformed the experts’ solutions in a total of 60 scenarios tested, with up to 19% shorter travel times.     

Toward intelligent driver-assistance and safety warning system

A major problem associated with the rapid growth in automotive production is an increase in traffic congestion and accidents, especially in big cities of China. To solve the problem, the government has been increasing funds for improving the traffic infrastructure, enforcing traffic laws, and educating drivers about traffic regulations. In addition, research institutes have launched R&D projects in driver assistance and safety warning systems. In particular, in 1999, the Chinese Academy of Sciences' Intelligent Control and Systems Engineering Center started the Intelligent Vehicle Platforms project. The project aims to promote the use of intelligent technology for safe, efficient, and smart vehicles and to prototype vehicular electronic and sensory products and systems for the Chinese automotive industry. One of the project's key objectives is to develop a vehicular application-specific operating system (vASOS). The National Science Foundation of China and the CAS Knowledge Innovation Program support the project. Supported by the Vehicular Embedded Computing Platform project, the Xi'an Jiaotong University (XJTU-"Jiao Tong" means transportation in Chinese) Institute of Artificial Intelligence and Robotics and the CAS have collaborated to develop intelligent driver-assistance and safety warning systems for passenger vehicles, particularly GPS-and vision-based systems.